12:19 PM PT -- Local authorities are currently looking for more information on the fake ads ... with the Philadelphia District Attorney's Office telling TMZ Sports it is investigating the matter.

Vice President Kamala Harris seemingly received a massive endorsement Monday ... with political ads dubbing her the official presidential candidate of the Philadelphia Eagles popping up around the city.

The only problem?? The team didn't approve the ad ... nor has it endorsed any presidential candidate -- and the city is now working on having all the posters removed.

The ads -- which displayed Harris in an Eagles helmet and holding a football -- were displayed at bus stops owned by Intersection Media ... leading to the company to issue a statement denying their legitimacy.

"We are aware that several of our bus shelters located in Philadelphia have been vandalized and that the paid advertising copy in each of those shelters has been replaced with an unauthorized copy," the company told NBC 10.

"While our bus shelters have locks that typically prevent the installation of unauthorized copy by non-Intersection staff, occasionally people find a way to unlock the ad box and insert unauthorized copy."

The team also addressed the situation ... calling them "counterfeit political ads" and vowing to get them removed.

While the advertisement was fake ... the URL on the poster was real -- helping direct fans to voting resources in New Jersey and Pennsylvania. There is no mention of Harris or Donald Trump anywhere on the page.

It is unknown who exactly was behind the posters ... as the city said, it was not a digital breach -- but someone physically put them at these locations.

The hope was to have all the counterfeit posters down by Tuesday morning.

Of course, Pennsylvania is a crucial state come November ... in an election that could be decided by just thousands of votes.